Library of Congress

“Libraries are the one American institution you shouldn't rip off.” -Barbara Kingsolver

Can't argue with that – especially because Washington DC's Library of Congress, which is the largest library in the world as far as book count, is free! It also happens to be the U.S.'s oldest federal cultural institution, and that means it has so much more than books. But speaking of books, it has the world's largest law library, originally established in 1832, and even a copyright office that helps sustain the nation's system of copyrighting.